This invention is directed generally to aphakic correction, and particularly to method and apparatus for surgical accomplishment of aphakic correction.
The human eye is a very complex organ comprising numerous interacting elements which gather, focus, and transmit light rays to nerve endings which eventually transmit the information to the brain for image perception. The eye includes a natural crystalline lens of avascular tissue, the transparency of which depends upon the critical regularity of its fibers and the balance of its chemical constituents. Obviously, there are innumerable factors which may interfere with lens makeup and thereby affect its transparent character. No matter what the reason, a condition of opacity in the lens, commonly called cataract, reduces the visual performance of the eye. When the visual performance is reduced to an unacceptable level, surgical cataract extraction becomes a necessity.
An eye without a lens, a condition called aphakia, is obviously defective from an optical point of view inasmuch as it cannot properly refract incident light rays. Aphakic correction may be accomplished in three ways:
1. Thick eye glasses worn in front of the eye;
2. Contact lenses worn on the eye; or
3. Artificial intraocular lens implant within the eye. It is this latter procedure with which the instant invention is concerned.
The structure and procedure of installing an intraocular lens is very critical because the elements which make up the eye are extremely sensitive and subject to irrepairable damage. Numerous experimental lens designs and surgical techniques for implantation have been tried through the years with varying degrees of success. Usually, the prior art procedures have been abandoned because the lens design and surgical techniques have proved to cause corneal damage and/or other manifestations of intraocular irritation. For example, in the late 1940's and early 1950's, H. Ridely conducted clinical experiments with an artifical intraocular lens which included a lens portion having foot-like projections extending radially away therefrom. This device was placed in the posterior chamber with the feet extending between the ciliary processes and the base of the iris. The lens proved positionally unstable because there was no means for fixing the location of the implant relative to the iris, and resulted in unsatisfactory amounts of irritation.
The device and procedure disclosed in U.S. Pat. No. 3,906,551 purports to solve the positional integrity problem; however, the implant must be sutured into position. Such suturing in a confined area is, at best, extremely difficult and potentially damaging to the eye, and is very often unsatisfactorily accomplished.
U.S. Pat. No. 3,866,249 discloses a posteriorly positioned prosthetic lens which has a multiplicity of forwardly projecting prongs. During surgical implantation, the prongs are extended through the iris to anchor the lens in position. While this arrangement certainly maintains positional integrity, the great number of prongs extending through and over the iris promote undesirable irritational characteristics, and the numerous fixation points have a tendency to distort the iris by pulling on it in numerous directions.